Bone grafts are often used to treat fractures, gaps in bones caused by trauma or infection, revision joint surgery, and oral/maxillofacial surgery. Bone grafts provide a framework into which the host bone can regenerate and heal. Once implanted, the bone cells weave into and through the porous microstructure of the bone graft to support the new tissue, blood cells and soft tissue as they grow to connect fractured bone segments.
Bone grafts can be prepared from a variety of materials, including bone harvested from a patient. Bone harvesting procedures, however, can result in significant cost and morbidity, including scars, blood loss, pain, prolonged operative and rehabilitation time and risk of infection. Furthermore, in some clinical settings, the volume of the graft site can exceed the volume of the available autograft. Accordingly, alternatives to autografts have been developed in an attempt to reduce the morbidity and cost of bone grafting procedures. Such alternative materials include purified or synthetic materials, such as ceramics, biopolymers, processed allograft bone and collagen-based matrices. These materials are typically used as carriers for bone marrow cells, and thus need to be prepared prior to implantation.
U.S. Pat. Nos. 5,824,084 and 6,049,026 disclose apparatus and methods for preparing implantable bone grafts having an enriched population of connective tissue progenitor cells. By infusing certain biologically active cells into a bone graft, it was found that the rate and quality of new bone formation is significantly improved. The bone grafts are prepared by flushing aspirated bone marrow one or more times to collect and concentrate the stem cells contained in the marrow into a bone matrix. While this procedure can be very effective, it can also be time consuming typically requiring around 20 minutes for the aspiration procedure, and an additional 20 minutes for the matrix preparation procedure.
Accordingly, there is a need for more efficient and effective methods and devices for preparing implantable substrates.